1. Field of the Invention
The present invention relates to a battery control circuit and an electronic device.
2. Description of Related Art
Portable electronic devices can include batteries (battery packs) for supplying operating power to device bodies. Such portable electronic devices are, for example, digital still cameras, video cameras, cellular phones, personal digital assistants (PDAs), and the like.
Into such a portable electronic device, a battery level detector for detecting the residual capacity of a battery is incorporated. In a method for detecting the residual capacity by the battery level detector, as shown in a block diagram of a battery control circuit of FIG. 5, voltage-dividing resistors R1 and R2 connected in series are connected to a battery 10 in parallel. The voltage appearing at the connection point between the voltage-dividing resistors R1 and R2 is detected by a microcomputer 20 (hereinafter referred to as “MC”). This MC 20 handles the detected voltage as information reflecting the residual capacity of the battery 10. Further, the MC 20 is constituted of a battery residual capacity detection LSI which has a built-in AD converter and to which an AD input terminal is added, and estimates the battery residual capacity based on the detected voltage (e.g., refer to Japanese Patent Application Laid-open Publication No. 2000-350371 (FIG. 9)). The battery residual capacity is displayed by, for example, a display device of the device body.
However, in the aforementioned conventional art, the voltage appearing at the connection point between the voltage-dividing resistors R1 and R2 is merely detected as information reflecting the residual capacity of the battery 10. The voltage detected in this way is not sufficient by itself to correctly estimate the actual residual capacity of the battery 10, which has a type-dependent difference and an individual difference.
Accordingly, in order to accurately estimate the residual capacity of the battery 10, for example, an advanced battery control function is employed in a notebook computer system. However, a system for realizing the advanced battery control function has a very complex configuration, and therefore cannot be employed in portable electronic devices and the like in which miniaturization and price reduction are required.